


In the Name of Science

by CassondraWinchester, lotrspnfangirl



Series: Destiel Morning Porn Club Fics [3]
Category: Supernatural
Genre: Alpha Castiel (Supernatural), Angel Mating, Angel Soulbonds, Bottom Dean, Grace Bonds, Human Dean, Knotting, Library Sex, M/M, Non-Traditional Alpha/Beta/Omega Dynamics, Sam Ships It, Soul Bond, Table Sex, Top Castiel, Wing Oil, angel rut
Language: English
Status: Completed
Published: 2017-07-15
Updated: 2017-07-15
Packaged: 2018-12-02 10:37:08
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,389
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/11507646
Author URL: https://archiveofourown.org/users/CassondraWinchester/pseuds/CassondraWinchester, https://archiveofourown.org/users/lotrspnfangirl/pseuds/lotrspnfangirl
Summary: “Do you know about angel ruts, Dean? Do you know what will happen if you let me have you? I don’t want to just use your body to quell my urges,” Cas leaned in even closer, pressed his forehead against the hunter’s, “I want tomateyou Dean, make you mine, and angels mate for life.” He met Dean’s verdant eyes. “No more one night stands, no other warm bodies in your bed. You will be mine and mine only, Dean Winchester. So tell me, do you still want this?”“Yes,” Dean whispered against Cas’ lips before closing the distance between them completely.





	In the Name of Science

**Author's Note:**

> We've decided that since we have a blast working together, we're going to keep doing it!! Here is our first Destiel Weekly Fic! You can find us on tumblr [here!](https://destiel-weekly.tumblr.com/) Once we figure out the proper set up, we would love prompts and comments. 
> 
> Feedback fuels the fire, so leave us some love ♥

Dean reached for his beer, sighing as he swirled the last sip around the bottom, and tossed it back. “I have nothing here, Sammy.”

Across the table, Sam glanced up from the large book he was reading, giving a sigh of his own. “I don’t know, Dean. The Men of Letters had everything archived pretty well. If it was here? We would’ve found it by now.” Sam spread his arm out over the tabletop where multiple books and scrolls lay in various states around them. 

“We could always try and capture one,” Dean suggested, and just like the last time he did so, Sam threw him a look. His brother slammed the book in front of him shut and ran a hand back through his hair. 

“We’re not going to capture one when we don’t even know what it _is_ nor how to kill it. Dean, I know you don’t want to, but I bet Cas would-”

“No,” Dean cut him off, shaking his head and pushing away from the table. He picked up their empty bottles and shook his head again. “Sam, Cas doesn’t want to be bothered with our regular old monster hunting, okay? He has enough shit to deal with.” 

Dean didn’t need to turn to see the look this time and he moved through the library to the hallway, heading for more beers. When he returned, Sam had his arms crossed and was staring at the doorway waiting for him. 

“Sammy, don’t, okay? Cas might know, sure, but we haven’t utilized all our resources yet. We could… I don’t know, go to the freaking library like we used to, spend some more time online, and-”

“And a few more people can get slaughtered and skinned alive and we can never find the six children that are missing,” Sam replied, calm as he reached for the beer and took a sip, his eyes never leaving Dean’s face. 

Dean glared and threw himself down in the chair. “If he’s pissed, I’m going to kill you.”

Sam rolled his eyes. “Dean, Cas is never pissed when we ask him for help. If he’s too busy, he won’t answer right now.”

Dean nodded absently, picking at the Margiekugel label. It wasn’t that he didn’t _want_ Cas’ help, having the angel around was always an okay in Dean’s book, but… “When he was here last week, did he seem off to you?”

Sam scratched the back of his neck and gave a half-hearted shrug. “He’s dealing with issues upstairs right now, it always kinds of makes him…” 

Sam shrugged again and Dean supplied, “Twitchy? Anxious? Absent minded?”

They sat in silence for a moment, remembering the last odd encounter where Cas had been so distracted talking to them in the kitchen, he hadn’t noticed he’d been leaning against the burner of the stove and had caught the sleeve of his coat on fire. He’d put it out instantly, a snap of his fingers repairing the damage, and then was gone the next moment without saying a word. 

Dean looked around the table and didn’t see anything within their proximity that could cause any harm if Castiel was still out to lunch, and then closed his eyes. 

“Cas? Hey, we need you down here for a moment. I was wondering if you-”

The fluttering of wings stopped him mid-sentence and Dean opened his eyes to see Sam staring wide eyed at the angel over his shoulder. Dean threw him a look and then turned around. Cas was standing there, his fingers twitching by his side as his eyes shifted around the room nervously. 

“What do you need?” His voice cracked as he spoke.

“It doesn’t matter,” Dean said and ignored the indignant noise coming from Sam behind him. He pushed out of the chair and took a step closer to the angel. “Are you okay, Cas?”

“I’m fine,” Castiel took a step back as Dean moved toward him as he repeated, “What do you need help with?”

Dean shook his head and moved forward again, reaching for Cas’ arm to stop him from moving away. He closed his hand around the angel’s bicep, a full body shudder moving through his friend. “Cas, what is wrong?” Dean asked and looked over his shoulder to Sam for help.

“Don’t,” Cas pulled his arm free from his friend’s hold. “Please, don’t touch me Dean,” he pleaded on a breathy sigh as he stumbled backwards. His hand reached up and wiped the sweat from his brow before dropping it to loosen the tie around his neck.

“Okay,” Dean said slowly, dropping his hand back to his side. “I don’t have to help you,” he tried to hide the pang of hurt in his voice, “Sammy can help if you would prefer.”

“No,” Castiel shook his head. “Sam can’t help with this.”

“Neither one of us can help you?” Sam asked from the table. He was standing now, but still gave enough space between himself and the angel. When Castiel stayed looking down at the ground, Sam met Dean’s eyes for a second before he clarified, “So I can’t help you… but Dean can. And you don’t want him to?”

Cas shifted from foot to foot as he ran his hand across the back of his neck, a nervous habit he had picked up from Dean. “I wouldn’t ask that of him,” the angel whispered.

Dean looked up at that, narrowing his eyes for a moment. “Cas… Whatever it is, I want to help. You know we would do anything for you.”

“This is different,” Cas shook his head before he met Dean’s eyes, “ _Very_ different.”

“Cas, come on,” Dean argued, opening his arms wide in offering. “I’m all yours! Just tell me how I can help you.”

“All mine,” a low growl rumbled from the angel’s chest, “I wouldn’t say such things to me right now, Dean.” Castiel stepped forward into the hunter’s personal space. He leaned in and took a deep breath, letting it out slowly as he whispered, “it’s dangerous to offer yourself up like that to an angel in rut.” 

Dean gasped softly as Castiel was instantly _right there_ , his chest pressing into Dean’s and his breath hot against Dean’s lips. He swallowed hard, the sound seeming too loud in his head and he was sure Castiel had heard it too. 

“Dean,” he heard Sam warn from behind him, but Dean’s eyes were locked with the intense blue just inches from him. This close, he could see the small beads of sweat against the angel’s forehead, on his upper lip, each breath causing fine tremors to run through his body. 

He was ethereal, powerful, and Dean both loved and hated to be reminded of what his friend truly was. Dean licked his lower lip, Castiel’s eyes darting down to follow the movement before they flicked back up and locked with Dean’s again. 

“I’m all yours,” Dean breathed out, confident in that fact if nothing else, “I want to help you.”

“No,” Cas whispered as he fought against his urges and took a small step back, his entire being screaming at him to take, to claim what was his. Instead he shook his head and replied softly as he stared at the ground again. “I won’t let you offer yourself up just to help me Dean.” He swallowed as his eyes darted up to meet bright green ones. “I want you to want this, like I want this. I don’t want to be an obligation.” 

Dean watched him carefully for a second, cleared his throat. “What makes you think I don’t?”

“Because,” Cas tilted his head to the side and furrowed his brows, his eyes never leaving Dean’s, “You’ve never given me a reason to think you do.”

Dean stared, could hear Sam shifting uncomfortably foot to foot behind him, and blew out a breath. “It’s never really… come up.”

Behind him, Sam snorted, but something flickered in Castiel’s eyes and Dean couldn’t tear his eyes away. Right now, Sammy and his opinion meant nothing. 

“Dean if you agree to this, if we do this, you need to be sure.” Cas took a small step forward and reached out his palm, cupping Dean’s cheek. “If you say yes, there's no going back.” 

Castiel swallowed and took a deep breath, being this close to Dean was hell on his senses. “I-” the angel ran his thumb across the hunter’s plush bottom lip, “I don’t think I will be able to stop once we start. So _please_ tell me you are sure you want this.”

The heat from Castiel’s hand on his face made Dean shiver again, and he could hear the pounding of his own heart, echoing through his head. He licked his lower lip and opened his mouth to answer, but nothing came out. He locked eyes with the angel and nodded instead. 

With Dean consenting, he wanted nothing more than to take him right then and there. But he had to be sure Dean knew what he was truly getting into. “Do you know about angel ruts, Dean? Do you know what will happen if you let me have you?” The small shake of Dean’s head prompted him to go on. “I don’t want to just use your body to quell my urges,” Cas leaned in even closer, pressed his forehead against the hunter’s, “I want to _mate_ you Dean, make you mine.” 

Cas tentatively closed the miniscule space between them, his lips brushing against the hunter’s as he continued, “And angels mate for life.” He met Dean’s verdant eyes. “No more one night stands, no other warm bodies in your bed. You will be mine and mine only, Dean Winchester.” 

Castiel quirked a brow, watching the slight tremor go through the hunter before him. “So tell me, Dean, do you still want this?”

“Dean,” Sam said again from behind, but Dean shook his head, brushing his brother off. Castiel narrowed his eyes at the slight shake and Dean’s hands shot forward, wrapping themselves in the lapels of the angel’s trench coat to keep him from moving back. 

He tugged the fabric gently, Castiel moving forward until they were pressed against each other. Dean searched the angel’s eyes for a moment, flicking down to his mouth, before he nodded again. “Yes,” he whispered against Cas’ lips before closing the distance between them completely. 

Castiel whimpered as Dean’s lips touched his, the whimper quickly turning into a growl as Dean’s lips parted on a sigh and the angel dipped his tongue inside, getting his first real taste. Cas wrapped his arms around Dean’s waist and walked him backwards as he deepened the kiss, only stopping when Dean’s lower back smacked against the table. The angel continued his explorations of Dean’s mouth as he hauled him up onto the table, ignoring Sam indignant squawk. 

When the angel broke the kiss, he and Dean were both breathless. He looked over at Sam who was watching the scene wide eyed and shocked. Cas slipped the trench coat from his body and let it fall to the floor before he spoke. “Sam, you may want to leave unless you want to watch me claim your brother. I’m showing great restraint, but soon I won’t care if you are in here or not.” 

“Sammy?” Dean added, panting as he watched Castiel start to undo the buttons of his cuffs, “Fuck. Off. Right. Now.”

“Guys, you’re in the library!” Sam argued, half horrified as Castiel got fed up with the buttons and simply ripped the fabric from his arms and chest, letting it flutter to the ground over his coat. “A bedroom, maybe?”

“Fuck,” Dean gasped, eyes wide as he took in the angel breathing heavily before him. Dean swallowed hard and braced his arms back on the table just seconds before Castiel surged forward again, nearly slamming into him and causing the table to skid back a few inches on the floor with a loud screech. 

“Do you know how long I have wanted this Dean?” The angel reached for Dean’s hand and placed it on his crotch, letting the hunter feel how hard he was. “How long I have wanted you,” he rasped.

“No time like the present, Cas,” Dean answered, squeezing him through the fabric of his suit pants. He hooked his legs around the back of Castiel’s knees, pushing himself forward and running his free hand up his chest, over his shoulder, to cup the back of his neck. “You have me now.”

“That I do.” With a flick of the angel’s wrist they were both completely naked and Cas crawled up onto the table with a feral look in his eyes, like a predator stalking his prey. Dean lay flat on the table, hissing when the cold wood touched his flesh. A wicked smirk spread across the angel’s lips as he leaned down and whispered into the hunter’s ear, “and what shall I do with you now that I have you, Dean?”

“Fuck, Cas,” Dean whispered, rolling his hips up, seeking the heat from the angel’s body. “Touch me.”

Castiel smiled, slow and sensual as he rolled his hips down, giving Dean the heat he was searching for. Dean groaned, reaching for Castiel’s shoulders to pull him closer. “You feel so fucking good.”

The angel growled as Dean pulled him closer and he continued to rut against the hunter, loving the feel of Dean’s rock hard cock sliding against his. “I’m going to fuck you,” he licked a long stripe up Dean’s throat, “and I’m going to claim you, Dean. Every creature in creation will know you are mine.”

“Always have been, Cas,” Dean confessed, letting his head thump back against the table to give Castiel better access to his throat. He groaned when he felt the brush of Cas’ teeth against his skin, his tongue following soon after to soothe the ache. “Ever since you pulled me out, its been you.” 

“So beautiful. I wanted you so bad, even back then. Your soul has always called to me,” Cas whispered against the tender flesh behind Dean’s ear. His hands trailed down the hunter’s sides, dancing along his ribs. “Even more beautiful laid out for me like this, wanting me to claim you as my mate.”

“Please, Cas,” Dean breathed out, shivering as Castiel’s fingertips trailed along his heated skin. “I’ve wanted you for so long, been afraid to tell you, to fuck up what we _did_ have…” Dean swallowed hard, pushing back the swell of emotion rising in his throat as he found Castiel’s eyes. “I need you.”

Those three little words broke Cas’ barely there restraint as he surged forward and claimed Dean’s lips again. He wanted more, needed more, his blood was screaming in his veins to spread the hunter’s legs and rut into him. But he couldn’t, not just yet. He wouldn’t risk hurting his mate.

Cas broke the kiss and with another flick of his wrist he was holding a small clear bottle with shimmery oil.

Dean’s eyes flicked to the glass bottle and then back at Cas. He shook his head slightly. “What is that?” he asked, looking back again, “That definitely isn’t Astroglide.” 

“It’s my wing oil,” Cas whispered shyly. “When angel’s mate, we like to mark our partner with our oil. Is… is that okay with you? If you would rather, we can use human lubricant.”

Dean’s eyes widened slightly and he opened his mouth to ask where ‘wing oil’ even came from, before he pushed it away. Another time, another place. “I think that’s pretty hot, Cas. No, I definitely want you to use that.”

“Good,” Cas rumbled, “Spread your legs for me, Dean.” 

The hunter spread his legs and Cas slicked up his fingers before running his hand up the inside of Dean’s thighs. The hunter’s breath caught as Cas pressed lightly against his tight pucker. Dean opened his mouth, seconds from protesting the teasing, when Cas pushed a finger past the tight ring of muscle, causing Dean to gasp instead. 

“Fuck, Cas.” He felt his body twitch around the intrusion, the pressure both perfect and not enough. He shifted his hips, trying to take more of Castiel’s finger, and whimpered when Cas pulled back instead. “I’m not going to break, Cas. I fucking need it, I need you. Please.”

Cas slicked up his fingers again and pressed two in this time, scissoring and spreading them wide, preparing the hunter for what was to come next. He plunged them in and out of Dean’s body, stroking his inner walls looking for that special spot that would make his mate’s body sing. He knew he had found it when Dean arched off the table and gripped Cas’ shoulders as breathy pleas of ‘more’ slipped past his lips.

Despite the momentary hesitation over using the wing oil, Castiel was the most confident partner Dean had ever been with. Every movement, every twist of Cas’ fingers inside of his body, every press of his lips ghosting over his throat and chest, every press of his skin against Dean’s own had every part of Dean thrumming with anticipation. He clung to Castiel as if his life depended on it, the angel making him feel things he hadn’t before. 

“Cas,” Dean gasped out, his entire body shaking as Castiel’s fingers pressed against that spot inside of him. “Fuck, Cas, I’m gonna-- you have to stop, I can’t-” 

“Tell me what you want, Dean.” Cas pressed a line of kisses across his jaw. “I will give you any and everything my beautiful mate, all you have to do is ask.”

Dean let out a soft cry as Castiel’s fingers kept insistent pressure against his prostate, his mouth still working along the side of Dean’s throat. 

“Fuck, Cas,” Dean’s fingers dug into the corded muscle of Cas’ shoulders, “I want you to fuck me. Please, Cas. I need it, I need _you_.”

Castiel twisted his fingers one more time for good measure, finding Dean’s mouth and kissing him soundly as he withdrew his hand, swallowing down the sound of protest falling from the hunter’s lips. Dean shifted, automatically angling his hips better to give Castiel access, and Cas smiled against his mate’s lips. 

“I’m ready, Cas,” Dean whispered against his mouth, hands trailing up the angel’s back and fingers coming up to tangle in the mess of dark hair. “I want you. Take me, angel.”

Castiel pushed himself up onto his knees between Dean’s spread legs and grabbed the bottle of wing oil. He squirted some into his hand and used it to coat his rock hard cock and the hunter groaned as he watched Cas fuck forward into his fist. Once the angel’s cock was covered in oil, he ran it up and down the crack of Dean’s ass before pressing it against his tight pucker. He slowly thrust forward, relishing in the soft gasps and moans it drew from Dean.

Dean’s head dropped back onto the table with a groan, Castiel was much bigger than he’d been expecting. He heard a soft chuckle above him and felt his cheeks flush as he realized he said his thought out loud. The embarrassment was short lived as Castiel circled his hips, pulling back and then shoving back in hard. Everything else went out the window - the only thing that mattered was right here, right now, him and Castiel. 

The angel slowly rocked in and out of Dean’s body loving the feel of the hunter underneath him writhing on the table begging for Castiel to go harder and faster, to claim him. Profanities and pleas fell from the hunter's lips as the angel slowly took him apart piece by piece.

“Cas, Cas, Cas,” the angel’s name was a chant on Dean’s tongue. He lifted his legs higher, gasping as the change of position allowed Castiel to sink into him deeper, and he locked his legs around Castiel’s hips, giving himself leverage to meet Castiel thrust for thrust. 

Castiel’s arms locked behind Dean’s shoulders, holding them tight. The slow roll of their hips leaving no doubt in Dean’s mind as to what this was. This wasn’t _fucking_ , this was -- 

“Cas,” Dean’s voice broke on his name, and he grabbed the back of Castiel’s head, pulling him forward and kissing him hard. 

The angel moaned into the kiss as he snapped his hips forward, dipping his tongue into the hunter’s mouth as he rutted into Dean’s pliant body. A low growl slipped past Cas’ lips as a delicious heat pooled low in his gut and he felt his knot start to swell and tug on Dean’s tight rim.

Dean’s groaned as his tongue returned the favor, mapping out the inside of the angel’s mouth. He gasped each time Castiel’s thick cock hit his prostate, his entire body singing out with pleasure. Then, something changed. Dean’s entire body tightened around Castiel’s body, his thighs squeezing into Castiel’s stomach, his arms around his shoulders, nearly stopping the angel’s movements. 

“What, is that,” Dean asked, eyes wide as he met the confused crystal blue ones looking down at him. Dean saw the moment realization dawned and he raised an eyebrow, body still tight around his mate’s.

“My knot,” Cas grunted as he snapped his hips forward. “That’s my knot Dean,” he panted, “It’s going to grow and lock inside your body, pump you full of my seed as I claim you as my mate.”

“Fuck,” Dean whispered, letting out a shaky breath. He gasped as Castiel pushed forward again, a more insistent pressure against his rim following. He met Castiel’s eyes again, searching them for a moment before he forced his body to relax. He knew Castiel wouldn’t do anything to hurt him, and as the angel reached for the back of Dean’s thighs, pushing his knees up towards his chest and sped up, his hips snapping forward, the uncomfortable pressure was gone.

Dean gasped, hands grabbing onto Castiel’s shoulders to hold on as the angel fucked into him harder, the table squeaking out it’s protest with each thrust. He felt each strike on his prostate like a bolt of lightning down his spine, and his gasps turned into soft cries. 

“Fuck, Cas, right there,” he gasped, eyes slamming closed as he bit down on his lower lip. He could feel the heat building, wondered if he could actually come untouched. 

The angel growled and gripped Dean’s hips tighter as he gave his mate exactly what he wanted. Fucking into Dean with intense fervor, Cas choked out a low moan as Dean’s inner walls spasmed around his cock. He buried his face in the crook of Dean’s throat and panted against his sweat soaked skin. The angels knot was growing with each thrust of his hips and Cas knew it wouldn’t be long before it caught. With a low growl and a few more hard snaps of his hips his thick knot locked inside of Dean’s body.

Dean cried out, his orgasm taking him by surprise as Castiel filled him completely. Castiel groaned against Dean’s throat as Dean’s cock spilt between them, and he could feel the heat of Castiel coming deep inside of him. 

“Cas,” Dean whispered, running his fingers back through Castiel’s sweat soaked hair and pulling his head up to find his lips. Castiel kissed him softly, taking his time opening Dean up slowly, until they broke apart, foreheads pressed together and sharing the air. 

Castiel groaned, shifting, his knot tugging against Dean’s rim and causing the hunter to gasp, his cock twitching against his stomach. Castiel whispered a few words, Dean quickly recognizing them as Enochian. He didn’t know what they meant and yet -- 

“And I, too, bind myself to you,” Dean whispered back, somehow knowing the words they spoke were one in the same. Castiel gasped and the air around them vibrated with energy. Dean matched the angel’s gasp as heat flooded his body, flowing through every inch, every sinew, every drop of blood and sweat. The heat flared, burning white hot, before disappearing as if it were never there, leaving Dean with an overwhelming sense of _home_ and _love_ and _belonging_.

“Castiel,” he whispered, eyes wide as he sought out his angel, his _mate_.

“I know Dean, I feel it too.” Cas pressed a chaste kiss to his mate’s lips. “You are _mine_ and I am _yours_ , always my love.”

Dean held Castiel closer, pressing his face into the curve of his neck. Castiel ran his hands slowly up and down Dean’s sides, and the hunter relaxed in the comfort of his angel. 

“It’s a silver knife, preferably into the heart but any vital organ should do.”

“What?” Dean pulled back, confused as to what the hell Castiel was talking about. 

“How to kill a lamia,” Castiel answered, pressing his lips to Dean’s forehead. “I am assuming that since the show is over and Sam is still standing here staring, he was looking for the answer to your original prayer.”

“The original- wait, Sammy?” Dean twisted his head around, finding his shell-shocked brother standing in the doorway, hands up in a placating manner. “Dude, what the fuck?”

“I just- you went and I- I mean, it was-” Sam stumbled over his words, cheeks flushed bright red as he tried to look anywhere other than Dean’s face. “It was… angel mating! It was scientific and I just-”

“Were leaving,” Castiel finished, sounding calm and almost bored, but both Winchester’s could hear the underlying command. 

“Yes! Leaving, I was just leaving,” Sam nodded and fled from the room. 

“You knew he was there the entire time, didn’t you?” Dean asked, focusing his attention back on his mate. 

“I did,” a small smirk spread across the angel’s lips. “I told you I wouldn’t be able to hold back once I started, nor would I care if he was in here.”

Dean glared half heartedly, then shook his head with a small laugh. “I can’t believe my little brother watched me have the best sex of my fucking life.”

Cas shrugged as best as he could in the position he was in. “If it makes you feel better, it was all in the name of science.”

“If Sammy writes a book, I’m going to kill you.”

Castiel just smiled and found Dean’s lips once more.


End file.
